Solder Interconnect Hierarchy for Wider TCB Process Windows

The patent divides the solder interconnect structure into multiple levels with different solder alloys. Level 1 uses high-temperature solder (e.g., Sn-Cu) for die-to-substrate bonding, while Level 2 uses low-temperature solder (e.g., Sn-Ag-In) for package-to-PCB bonding. This segmentation allows each level to be optimized for its specific thermal requirements, enabling precise control of solder height and volume at each level without subjecting the entire structure to uniformly high temperatures that would cause corrosion and metallization dissolution.

Different solder alloys with appropriate melting temperatures are assigned to different locations in the interconnect hierarchy. The local solder composition is tailored to the specific thermal processing requirements of each bonding level, allowing optimal process window and solder joint quality at each location without compromising the reliability of other levels.

The patent segments the solder interconnect system into multiple levels, where each level can be independently optimized for its specific pitch and pad size requirements. Level 1 handles die-to-substrate connections with one set of solder parameters, while Level 2 handles package-to-PCB connections with different solder parameters. This segmentation allows the system to accommodate heterogeneous components with mixed pitch and pad sizes without compromising solder joint precision.

Each level of the interconnect hierarchy uses solder alloys and process parameters locally optimized for its specific application. This local optimization enables precise control of solder bump height and volume even when connecting components with vastly different pitch and pad size requirements, maintaining manufacturing precision across diverse package architectures.